Ignition distributors



y 1970 w. H. COOKSEY ET Al. 3,510,608

IGNITION DISTRIBUTORS 3 Sheets-Sheet 1 Filed Jan. 51, 1968 ATTORNEYS May 5, 1970 w. H. COOKSEY ET AL 3,510,608

IGNITION DISTRIBUTORS Filed Jan. 51, 1968 3 Sheets-Sheet 2 INV NTOR g.

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ATTQRNEYS May 5, 1970 w. H. COOKSEY ETAI. 3,510,608

IGNITION DISTRIBUTORS Filed Jan. 31, 1968 3 Sheets-Sheet 3 W /8\I T/Z v PRIOFURT INVE NTOR ATTORNEYS United States Patent 3,510,608 IGNITION DISTRIBUTORS William Harold Cooksey and Albert Henry Ball, Walsall,

England, assignors to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed Jan. 31, 1968, Ser. No. 701,890 Claims priority, application Great Britain, Feb. 14, 1967, 7,008/ 67 Int. Cl. H01r 39/46 US. Cl. 200-19 Claims ABSTRACT OF THE DISCLOSURE This invention relates to ignition distributors for use in road vehicles, of the kind wherein the casing of the distributor also supports the engine driven contact breaker and a capacitor connected across the contact breaker.

The present practice with distributors of this kind is I to provide an input terminal on the casing, a lead being taken from this input terminal to an intermediate terminal within the casing which is electrically connected to one contact of the contact breaker. Alternatively, the input lead can be taken through a protective insulating bush on the casing directly to the intermediate terminal, no terminal being provided on the casing. Another lead is then taken from the intermediate terminal to one side of the capacitor, and the other side of the capacitor and the other contact of the breaker are interconnected, usually by earthing them through the casing of the distributor. It has now been found that this particular arrangement reduces the beneficial effect of the capacitor in reducing radio interference because of the inductance of the lead connecting the intermediate terminal to the capacitor, and the object of the invention is to minimise this disadvanta e.

according to the invention, in a distributor of the kind specified, an input lead is connected to one side of the capacitor, said one side of the capacitor also being connected through a further lead to an intermediate terminal electrically connected to one contact of the contact breaker, and the other contact of the contact breaker and the other side of the capacitor being electrically interconnected.

An example of the invention is illustrated in the accompanying drawings in which FIG. 1 is a sectional plan view of an ignition distributor, FIG. 2 is a plan view of the contact breaker assembly shown in FIG. 1 but to a larger scale, FIG. 3 is an exploded perspective view of part of the assembly shown in FIG. 2 but to an enlarged scale, FIG. 4 is a sectional view of the capacitor shown in FIG. 2 also to an enlarged scale, FIG. 5 is a perspective view of the connector shown in FIG. 4, FIG. 6 is a sectional view of the connector shown in FIG. 5 in its unstressed position, its stressed position being indicated in dotted lines, FIG. 7 is a circuit diagram of the arrangement shown in FIGS. 1 to 6 and FIG. 8 is an equivalent circuit diagram of the prior art.

Referring to FIGS. 1 to 6 there is provided a distributor including a casing 10 having secured therein a base plate 10a. A contact breaker assembly is housed within the casing 10 and includes a plate 11 which is parallel with the plate 10a and which is mounted for angular movement with respect of the cam shaft 10b of the distributor, about a pivot post 11a. Supported by the plate 11 is a fixed contact 12 having associated therewith a movable contact 13, the fixed contact being electrically connected to the plate 11. The movable contact 13 is carried by an insulating cam follower 14 which is pivotally engaged with a post 14a upstanding from the plate 11. One end of a conductive spring 15 is secured to the cam follower 14, and is electrically connected to the contact 13 by a conductive strap 13a, the other end of the spring 15 being engaged with an insulating block 16 of channel shaped cross section which is secured to a lug 17 integral with the plate 11. The spring 15 in use urges the cam follower 14 into engagement with the cam shaft of the distributor and the arrangement is such that rotation of the cam shaft causes the movable contact 13 to move into and out of engagement with the fixed contact 12.

The spring 15 extends beyond the block 16 and its end portion 15a is bent to lie substantially parallel with the main portion of the spring 15. A blade connector 19 having a lead 21 connected thereto is gripped between the main portion and the portion 15a of the spring 15 and thereby serves to electrically interconnect the lead 21 and the contact 13 through the spring 15.

The other end of the lead 21 is electrically connected to one limb 24 of a resilient conductive connector 22. The connector 22 is in the form of a generally V shaped member 23 having integral limbs 24, 25. The limb 24 is formed with a longitudinally extending slot 26, the end 27 of which is adjacent the free end of the limb 24, and is semi-circular, its centre of curvature lying on the longitudinal centre line of the limb 24. The limb 25 is formed with a circular hole 28 of radius equal to the radius of the end 27 of the slot 26 in the limb 24, the centre of the hole 28 lying on the longitudinal centre line of the limb 25. The slot 26 and the hole 28 are so arranged that if the member 23 is flexed so that the limbs 24, 25 are parallel, then end 27 of the slot 26 and the hole 28 will not be co-axial. The limb 24 of the member 23 also has connected thereto one end of a second lead 29, the other end of which is connected to a terminal 30 on but insulated from the casing 10. In use, the terminal 30 is connected through the primary winding of an ignition coil to the battery of a road vehicle in which the contact breaker is utilized. An alternative arrangement is to dispense with the terminal 30 and pass the lead 29 through a protective insulating bush on the casing directly to said primary winding.

The contact breaker assembly further includes a capacitor 18 having a first terminal constituted by its casing and a second terminal in the form of a cylindral post 31 with which the connector 22 is engaged.

In order to interengage the post 31 and the connector 22, the connector 22 is flexed so that the limbs 24, 25 extend parallel to one another, the post 31 is then inserted through the hole 28 and the slot 26. The post 31 has a diameter slightly less than the diameter of the hole 28 and the width of the slot 26, and is formed with a circumferential groove 32. The connector 22 is then released and by virtue of their resilience the limbs 24, 25 spring apart thereby engaging part of the periphery of the hole 28 and the part 27 of the slot 26 within the groove 32.

In use the plate 11 and the casing of the capacitor 18 are earthed through the plate 10a. Thus the movable contact 13 is connected to the battery and the capacitor 18 is connected across the contacts 12, 13.

FIG. 7 illustrates the electrical connections shown in FIGS. 1 to 6. The lead 29 extends directly from the terminal 30 (or the primary winding where the terminal 30 is omitted) to the capacitor 18, and the lead 21 runs from the capacitor 18 to an intermediate terminal constituted by the connector 19, from which a connection is made to the contact 13. In the prior art, indicated in FIG. 8, the terminal 30 (or the lead from the primary winding) is connected to the intermediate terminal 19', which is connected to the contact 13 as in FIG. 7. Another lead 40 connects the terminal 19 to the capacitor. It has been found that an unnecessarily high level of radio interference is produced by a distributor with connections as shown in FIG. 8 by virtue of the inductance of the lead 40 between the intermediate terminal 19 and the capacitor 18. The eifect of the arrangement shown in FIG. 7 is that the inductance of the lead 40 in FIG. 8 in series with the capacitor 18 is eliminated, thus allowing the capacitor 1 8 to form a shunt path of reduced impedance across the contacts 12, 13 which of course produce the radio frequency interference.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. In an ignition distributor containing a casing, a pair of contact breakers and a capacitor, the improvement comprising an input lead electrically connected to one side of said capacitor; a further lead connected from said one side of said capacitor to an intermediate terminal which is electrically connected to one of said contact breakers; said other contact breaker electrically connected to the other side of said capacitor, whereby directly electrically connecting said input to said one side of the capacitor the impedance of the shunt path between said contact breakers is reduced thereby reducing radio interference.

2. A distributor as claimed in claim 1 wherein said 3. A distributor as claimed in claim 1 wherein said input lead extends from said one side of the capacitor through a protective insulating bushing on said casing to a primary Winding of an ignition coil.

4. A distributor as claimed in claim 1 wherein said one of the contact breakers is movable and said other contact breaker is fixed, said other contact breaker being earthed through said casing to said other side of the capacitor; and further including a resilient connector on said one end of the capacitor, which connector electrically connects said capacitor to said input lead and further lead.

5. A distributor as claimed in claim 4 wherein said one side of the capacitor is in the form of a cylindrical conductive post and said resilient connector is in the form of a V shaped member the limbs of which are formed with respective holes, the arrangement being such that the limbs of said V shaped member can be flexed to a position wherein they are substantially parallel so as to allow said cylindrical conductive post to be inserted through said holes, said limbs then being released so that they flex to a position whereinsaid post is engaged by parts of the walls of the holes in the limbs respectively.

References Cited UNITED STATES PATENTS 2,896,035 7/ 1959 Harrington et al 200- 2,979,577 2/1961 Adler 200-19 XR 2,989,601 6/1961 Cooksey 200-19 XR 2,991,338 7/1961 Mason 200-31 3,221,116 11/ 1965 McAllister 200-27 ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner 

